The use of silver for medicinal purposes dates back to the eighth century ce and is still in use today.1- 3 Generalized argyria is characterized by slate-gray to blue discoloration of the skin caused by cutaneous deposits of silver particles after long-term ingestion of solutions containing colloidal silver ingredients or silver salts.1- 3 The skin discoloration is more prominent in sun-exposed areas and is usually permanent. There is no widely accepted effective treatment for the skin discoloration of argyria.1

In 1999, the US Food and Drug Administration (FDA) responded to the widespread use of colloidal silver as a remedy for many ailments.4 The FDA stated:

over-the-counter drug products containing colloidal silver ingredients or silver salts for internal or external use are not generally recognized as safe and effective and are misbranded…products containing colloidal silver ingredients or silver salts are being marketed for numerous serious disease conditions and FDA is not aware of any substantial scientific evidence that supports the use of over-the-counter colloidal silver or ingredients or silver salts for these disease conditions.4(p44653)

Despite the FDA’s warning, colloidal silver remains accessible from at least 2 major online retailers and is being marketed as a dietary supplement that will improve health. The product description of one ingestible liquid product containing colloidal silver from Walmart.com claims it can “eliminate toxins, poisons and fungi from your body” and that it will “keep your system’s defenses against toxins and viruses high” (both quotations from http://url.ie/ylm7).

Methods

To investigate the current availability of colloidal silver solution in one major online marketplace, the term colloidal silver was searched on Amazon.com on June 13, 2014. The search yielded 2286 different colloidal silver products. The products were then limited to only those listed in the health and personal care department, which yielded 1010 different products. The results were then limited to only liquid colloidal silver products, which yielded 149 different products; only these ingestible liquid colloidal silver products were analyzed. The search results were sorted by relevance, not by rating.

Results

Twenty-four different ingestible liquid products containing colloidal silver were listed on the first page of the search results; only products on this first page of the results that had at least 10 consumer reviews were included for analysis. These criteria yielded 12 colloidal silver products with a combined total of 606 individual customer reviews (mean, 50.5 reviewers per product). The mean consumer rating of these 12 products was 4.38 of a possible maximum rating of 5 stars.

Discussion

The availability of colloidal silver solution as a health and personal care product is concerning. With the use of an online marketplace, colloidal silver can be easily obtained, and consumers can be influenced by the favorable product reviews. It is important that a patient’s medical history include information about over-the-counter medications, dietary supplements, and complementary and alternative medications. The most common adverse effect of long-term colloidal silver ingestion is argyria. Advising patients against further use can prevent worsening of skin discoloration and development of renal, hepatic, and neurologic problems that have been reported after long-term ingestion of colloidal silver.4 In addition, the FDA warning made 16 years ago should be reemphasized and consideration should be given to adding colloidal silver to the list of the agency’s Unapproved Drugs Initiative since it poses a potential safety risk and lacks evidence of being effective.